Fan Device

ABSTRACT

A fan device includes: a fan housing configured with a receiving space defined among opposite top and bottom walls, and a surrounding side wall; and a fan impeller mounted in the receiving space, disposed adjacent to an air outlet in the top wall and operable to rotate about a central axis transverse to the top and bottom walls of the fan housing. The fan impeller includes a hub body disposed coaxially with the central axis, and a plurality of angularly spaced apart fan blades extending outwardly and radially from the hub body. An angular distance between each adjacent pair of the fan blades is different from that of any other adjacent pair of the fan blades.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Application No. 098143619, filed on Dec. 18, 2009.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a fan device, and more particularly to a fan device capable of reducing acoustic noise.

2. Description of the Related Art

A conventional fan device includes a fan impeller mounted in a fan housing. The fan impeller includes a hub body, and a plurality of angularly spaced apart fan blades extending outwardly and radially from the hub body. However, in such a configuration, greater acoustic noise occurs during rotation of the fan impeller at a speed within a certain speed range.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a fan device that can overcome the aforesaid drawback of the prior art.

According to the present invention, a fan device comprises:

a fan housing configured with a receiving space, and having a bottom wall formed with an air inlet in spatial communication with the receiving space, a top wall formed with an air outlet in spatial communication with the receiving space, and a surrounding side wall transverse to and interconnecting the top and bottom walls, and cooperating with the top and bottom walls to define the receiving space thereamong; and

a fan impeller mounted in the receiving space in the fan housing, disposed adjacent to the air outlet in the top wall of the fan housing, and operable to rotate about a central axis that is transverse to the top and bottom walls of the fan housing, the fan impeller including a hub body disposed coaxially with the central axis, and a plurality of angularly spaced apart fan blades extending outwardly and radially from the hub body, an angular distance between each adjacent pair of the fan blades being different from that of any other adjacent pair of the fan blades.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:

FIG. 1 is a schematic top view showing the first preferred embodiment of a fan device according to the present invention;

FIG. 2 is a schematic sectional view of the first preferred embodiment taken along line II-II in FIG. 1;

FIG. 3 is a schematic bottom view showing the second preferred embodiment of a fan device according to the present invention;

FIG. 4 is a perspective view showing the second preferred embodiment without a fan impeller;

FIG. 5 is a partly schematic sectional view showing the second preferred embodiment;

FIG. 6 is a schematic top view showing the third preferred embodiment of a fan device according to the present invention without a fan impeller; and

FIG. 7 is a schematic top view showing a variation of the third preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.

Referring to FIGS. 1 and 2, the first preferred embodiment of a fan device according to the present invention is shown to include a fan housing 1, and a fan impeller 2.

The fan housing 1 is configured with a receiving space 10, and has a bottom wall 11, a top wall 12 and a surrounding side wall 13. The bottom wall 11 is formed with an air inlet 111 in spatial communication with the receiving space 10. The top wall 12 is formed with an air outlet 121 in spatial communication with the receiving space 10. The surrounding side wall 13 is transverse to and interconnects the top and bottom walls 12, 11, and cooperates with the top and bottom walls 12, 11 to define the receiving space 10 thereamong. In this embodiment, the fan housing 1 further includes a connecting member 14 and a plurality of connecting ribs 15. The connecting member 14 is placed in the receiving space 10, and is disposed adjacent to the air inlet 111. The connecting ribs 15 interconnect the connecting member 14 and the surrounding side wall 131.

The fan impeller 2 is mounted in the receiving space 10 in the fan housing 1, is disposed adjacent to the air outlet 121 in the top wall 12 of the fan housing 1, and is operable to rotate about a central axis (X) that is transverse to the top and bottom walls 12, 11. The fan impeller 2 includes a hub body 21, and a plurality of fan blades 22 extending outwardly and radially from the hub body 21. It is noted that an angular distance (Φ) between each adjacent pair of the fan blades 22 is different from that of any other adjacent pair of the fan blades 22. An air passage is formed between each adjacent pair of the fan blades 22.

In use, rotation of the fan impeller 2 draws air to flow from the air inlet 111 toward the air outlet 121 through the air passages, as indicated by solid-line arrows in FIG. 2.

Since the angular distances (Φ) are different from each other, noise with different frequencies occurs when air flows through the air passages, thereby avoiding accumulation of noise with the same frequency. According to experimental measurement results, acoustic noise about 25.1 dB caused by the fan device of the present invention during operation is less than that (about 45.9 dB) of the conventional fan device with angularly equidistant fan blades. Therefore, the fan device of the present invention can be operated with reduced acoustic noise.

FIGS. 3 to 5 illustrate the second preferred embodiment of a fan device according to this invention, which is a modification of the first preferred embodiment. As composed to the first preferred embodiment, the connecting member 14 and the connecting ribs 15 are dispensed with. Furthermore, the fan device further includes an air-guiding unit 3.

The air-guiding unit 3 is mounted fixedly in the receiving space 10 in the fan housing 1, and is disposed adjacent to the air inlet 111 in the bottom wall 11 of the fan housing 1. The air-guiding unit 3 includes a center connecting member 31 disposed coaxially with the central axis (X) , and a plurality of air-guiding blades angularly spaced apart from each other and interconnecting the central connecting member 31 and the surrounding side wall 13 of the fan housing 1. An angular distance (θ) between each adjacent pair of the air-guiding blades 32 is different from that of any other adjacent pair of the air-guiding blades 32. In this embodiment, the center connecting member 31 includes a circular cap body 312, and a tube body 311 extending integrally from the cap body 312 toward the hub body 21 and disposed coaxially with the central axis (X).

When the fan impeller 2 is driven to rotate, air flowing from the air inlet 111 is guided by the air-guiding blades 32, and then flows toward the air outlet 121 through the air passages, as indicated by solid-line arrows in FIG. 5. Therefore, due to the presence of the air-guiding unit 3, air pressure produced by the fan device can be enhanced. Furthermore, since the angular distances (θ) are different from each other, acoustic noise caused by the fan device can be further reduced.

FIG. 6 illustrates the third preferred embodiment of a fan device according to this invention, which is a modification of the second preferred embodiment. As compared to the second preferred embodiment, the air-guiding unit 3′ further includes a plurality of auxiliary air-guiding blades 33 extending inwardly and radially from the surrounding side wall 13 of the fan housing 1 toward the central connecting member 31. Each auxiliary air-guiding blade 33 is disposed between a corresponding adjacent pair of the air-guiding blades 32, and is spaced apart from the corresponding adjacent pair of the air-guiding blades 32 and the central connecting member 31. In this embodiment, the auxiliary air-guiding blades 33 have the same length.

FIG. 7 illustrates a variation of the third preferred embodiment, wherein each of the auxiliary air-guiding blades 33 of the air-guiding unit 3′ has a length different from that of any other one of the auxiliary air-guiding blades 33.

While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

1. A fan device comprising: a fan housing configured with a receiving space, and having a bottom wall formed with an air inlet in spatial communication with said receiving space, a top wall formed with an air outlet in spatial communication with said receiving space, and a surrounding side wall transverse to and interconnecting said top and bottom walls, and cooperating with said top and bottom walls to define said receiving space thereamong; and a fan impeller mounted in said receiving space in said fan housing, disposed adjacent to said air outlet in said top wall of said fan housing, and operable to rotate about a central axis that is transverse to said top and bottom walls of said fan housing, said fan impeller including a hub body disposed coaxially with the central axis, and a plurality of angularly spaced apart fan blades extending outwardly and radially from said hub body, an angular distance between each adjacent pair of said fan blades being different from that of any other adjacent pair of said fan blades.
 2. The fan device as claimed in claim 1, further comprising an air-guiding unit mounted fixedly in said receiving space in said fan housing and disposed adjacent to said air inlet in said bottom wall of said fan housing, said air-guiding unit including a center connecting member disposed coaxially with the central axis, and a plurality of air-guiding blades angularly spaced apart from each other and interconnecting said central connecting member and said surrounding side wall of said fan housing, an angular distance between each adjacent pair of said air-guiding blades being different from that of any other adjacent pair of said air-guiding blades.
 3. The fan device as claimed in claim 2, wherein said air-guiding unit further includes a plurality of auxiliary air-guiding blades extending inwardly and radially from said surrounding side wall of said fan housing toward said central connecting member, each of said auxiliary air-guiding blades being disposed between a corresponding adjacent pair of said air-guiding blades and being spaced apart from the corresponding adjacent pair of said air-guiding blades and said central connecting member.
 4. The fan device as claimed in claim 3, wherein said auxiliary air-guiding blades of said air-guiding unit have the same length.
 5. The fan device as claimed in claim 3, wherein each of said auxiliary air-guiding blades of said air-guiding unit has a length different from that of any other one of said auxiliary air-guiding blades. 